This invention relates to a printing machine, which is used for printing desired information, such as bar codes, on a strip of labels, tickets, tags or the like. The printing machine is preferably portable and desk type.
In known label printing systems, prices, shop numbers, production dates, and other information about various commodities are printed on labels, tickets, tags, or the like (hereinafter referred to as labels) by printing machines installed in supermarkets or department stores. The printed labels are attached to the commodities to be sold. The printed labels provide information to the customers about commodities to be purchased and also provide information to the store clerks for counting and totalizing of commodities. When they are capable of being read with the naked eye, the accuracy and clarity of printed indicia are regarded as satisfactory for the above purposes.
In recent years, a computerized POS (point of sale) system has been adopted in large supermarkets for foods and other household goods. Information about the commodities being sold is indicated by bar codes imprinted directly on the casings, boxes or bags of commodities, or on labels which are attached to the commodities to be sold. The bar code system was developed mainly for what is called source marking, where the bar codes are directly printed on boxes and bags as they are produced.
Each character of a bar code is represented by two parallel dark bars and two light spaces, and a bar code is assembled by arranging the bars and spaces in side-by-side relation. In the symbol marks of the Universal Product Codes established by American Supermarket Institute, the required length of a dark bar is about 23 mm, the breadth of one character is 2.311 mm and the tolerance of the breadth of the character is .+-. 0.096 mm. Hence, a code must be printed with precision.
The bar codes appearing on the commodities are optically read when the goods are purchased. This performs useful purposes in the administration of sales, inventory and store managing. In order to read the bar codes with an optical character reading means, the bar codes must be printed precisely.
Since factories can install precise and large-scale printing machines for a source marking system, they can do precise bar code printing. However, it is impractical to install large printing machines for printing bar codes in shop fronts and supermarkets. Therefore, label printing machines which are able to print bar codes on labels in a store and attach the printed labels to commodities in the store are eagerly desired.
In known printing machines of this type, the outside of a cylindrical drum carries types for printing several bar code characters. The drum is rotated to shift the desired type to the print position. The type is then pressed against a label strip. A carbon-polyethylene ribbon is interposed between the type and the label strip. A length of the carbon-polyethylene ribbon of the same length as the label is consumed in every printing. The above type of printing machine is not widely used, because it has the following disadvantages:
a. Printing speed is low. PA1 b. Printing cost is high. PA1 c. Large logical circuits and driving members are required for rotating and selecting a drum at every printing. PA1 d. The size and weight of the machine are quite large and the machine cannot be easily carried. PA1 e. The printing machine is expensive.
As a result of the foregoing problems, bar code printing at stores and shops was tried using the conventional printing machines that are used for printing the prices and other information about commodities on the labels for the commodities. However, precise printing of bar codes on the label strips was not attainable with these conventional machines.